Fig. 3From: Lead-free perovskite solar cells using Sb and Bi-based A3B2X9 and A3BX6 crystals with normal and inverse cell structuresSEM images of A3B2X9 films [(CH3NH3)3Bi2I9: (a, b); (CH3NH3)3Sb2I9: (c, d); (CH3NH3)3SbBiI9: (e, f)] grown on different substrates [TiO2: (a, c, e); NiO: (b, d, f)]Back to article page